1. Field of the Invention
The present invention is related to a fan with spiral supercharging device and particularly to a device capable of increasing pressure of fluid outward the fan.
2. Brief Description of the Related Art
Referring to FIGS. 1 and 2, the conventional fan provides a hub 11 and a plurality of fan blades 12. The hub 11 is cylindrical with a flat facial end 111 having an area identical to the rear end thereof. The fan blades 12 surrounding the hub 11 each have a front edge 121 and a rear edge 122 with a gap 13 between every two adjacent fan blades 12, that is, the respective fan blade 12 is unshielded with another fan blade 12 next to it.
The problem of the preceding conventional fan is in that when the fan is in operation, the gap 13 becomes flow passage and fluid can pass outward through the gap 13. However, the fluid being acted by the fan blades 12 becomes less and it leads to pressure of the fluid moving outward being small. In addition, the fluid flows axially and diffuses outward immediately instead of gathering as a fluid beam moving outward.